diff --git a/test/harness/isConstructor.js b/test/harness/isConstructor.js
new file mode 100644
index 0000000000..cc3a134997
--- /dev/null
+++ b/test/harness/isConstructor.js
@@ -0,0 +1,31 @@
+// Copyright (C) 2017 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: >
+    Including isConstructor.js will expose one function:
+
+      isConstructor
+
+includes: [isConstructor.js]
+---*/
+
+assert.sameValue(typeof isConstructor, "function");
+
+assert.sameValue(isConstructor(), false);
+assert.sameValue(isConstructor(undefined), false);
+assert.sameValue(isConstructor(null), false);
+assert.sameValue(isConstructor(123), false);
+assert.sameValue(isConstructor(true), false);
+assert.sameValue(isConstructor(false), false);
+assert.sameValue(isConstructor("string"), false);
+
+assert.sameValue(isConstructor({}), false);
+assert.sameValue(isConstructor([]), false);
+
+assert.sameValue(isConstructor(function(){}), true);
+assert.sameValue(isConstructor(function*(){}), false);
+assert.sameValue(isConstructor(() => {}), false);
+
+assert.sameValue(isConstructor(Array), true);
+assert.sameValue(isConstructor(Array.prototype.map), false);